The proposed research will examine the specificity of hormonal activation of male social behaviors from several different perspectives. First, the hormonal control of a wide variety of male social behaviors, including courtship, copulatory, aggressive, and paternal behaviors, will be examined to determine if several functionally related behaviors (e.g., aggressive behavior) are controlled by the same hormone(s), or if each behavior is activated independently of the others. Second, the occurrence of particular behaviors will be measured in several social contexts (e.g., chasing in sexual and aggressive encounters), to determine if the hormonal control of a particular behavior is invariant, or if one hormone activates the behavior during sexual interactions and a different hormone activates the behavior during aggressive interactions. Third, these questions will be examined in two species of songbirds, zebra finches and redwinged blackbirds, whose reproductive strategies and life histories differ from one another and from previously studied species to determine if differences between species in the specificity of hormonal activation of male social behavior are related to interspecies differences in reproductive strategies. Finally, a variety of biochemical techniques will be used to determine which metabolites of testosterone are active within specific neural and peripheral target tissues involved in the production of different male social behaviors. Abnormalities in endocrine control mechanisms and the ensuing behavioral dysfunction cannot be dealt with adequately without a better understanding of the functioning of these mechanisms. The integrative approach used in this research should increase our understanding of the organization and functioning of endocrine control mechanisms, their specificity, and how hormones interact to produce the full pattern of male social behavior.